I'm having a serious problem. I had a 20-40 that was working fine, but I wanted more pressure so I got a new 40-60. When I got everything hooked up, I was only generating about 40 psi and it would go no higher. Just to be clear, I did raise the pressure tank to 38 psi before starting the pump. I shut the pump down and cleaned out the tube to the bottom of the switch and the pressure gauge and started it back up, now its only hitting about 18 psi. I put the old switch that worked fine, same thing. I took the small tube off and cleaned it again with no change. I'm at a loss here and I've got very little water pressure. HELP

Sorry you didn't get in touch sooner.
We could have given you instructions on how to set up the PSI on your old control box and saved you the expense of a new one and the pickle you now find yourself in. Oh well!
Let's start from scratch and double check the wiring.
Hings You'll Need
Square D GFCI outlet
Screwdriver
Wire strippers
Electrical pliers
1
Turn off the circuit breaker that controls the circuit in which you will be installing the GFCI outlet.
2
Remove the Square D GFCI outlet from the packing box. The back of the GFCI outlet will be marked "LINE" and "LOAD." Wiring will be attached to the "LINE" side screws only. The "LOAD" side is reserved for fixtures or other outlets attached beyond this outlet in the circuit. Fixtures and other outlets are protected through the GFCI outlet.
3
Confirm the presence of hot, neutral and ground wires in the junction box where the GFCI outlet will be installed and wired. Strip the insulation on the three wires to expose 3/4" of wire.
4
Complete the initial wiring of the stand-alone outlet. Connect the neutral (white) wire to the "Line/Neutral" set screw (silver). Connect the hot (colored) wire to the "Line/Hot" set screw (gold). Connect the ground (green) wire to the ground set screw (green).
5
Connect any protected devices to the " set screw (gold). Connect the ground (green) wire to the ground set screw (green).
5
Connect any protected devices to the " side before installing the GFCI in the junction box. Connect the device's neutral (white) wire to the "Load/Neutral" side before installing the GFCI in the junction box. Connect the device's neutral (white) wire to the "Load/Hot" set screw (silver). Connect the device's hot (colored) wire to the "Test" set screw (gold). Connect the device ground (green) wire to the ground set screw (green).
6
Install the outlet to the box using the two 6/32-inch mounting screws provided, and install the cover plate.
7
Turn the breaker back on and test the GFCI outlet by pushing its "Reset" button. If devices are attached to this outlet, then they will not function when the test is successfully performed prior to Reset.
Check out your work and get back to me and we'll go from there. Good luck, Tom

Is your pump above ground or in the well? I think your switch must be OK as it's turning the pump on, which is all it can do. The problem is elsewhere. BTW, I'm assuming you mean the pressure is getting to 18# with the pump still running.

Just out of curiosity, how did the discussion get swapped to installing a GFCI outlet?